The invention relates to a floating island for extracting or processing gas.
The publication "Floating Offshore LNG Liquefaction Facility--A Cost Effective Alternative", author M. C. Terry, of the Global Marine Development Inc., published on the occasion of the Seventh Annual Offshore Technology Conference in Houston, Texas on 5th-8th May 1975, describes gas extraction in coastal regions wherein the gas is transported to the shore by way of a pipeline laid on the bottom of the sea. The transported gas is liquefied on shore in a stationary installation, and the liquefied gas is then shipped in tankers. The investment involved in transporting the non-liquefied gas to shore is considerable. The pipeline and the liquefaction installation are fixed in one place. As a result, such an installation can be justified only when large deposits of natural gas are available, preferably near the coast. This prior art installation is not suitable for using low yield natural gas deposits.
The publication authored by Terry also describes a liquefaction facility installed on a ship which, for safety reasons is not anchored immediately over the gas field but in the immediate vicinity thereof. The gas passes by way of a sea bed pipeline to the ship where it is liquefied. The ship, however, has limited storage capacity. As a result, the intermediate storage tanks on the ship have to be periodically emptied by relatively small tankers. An important disadvantage of this liquefaction proposal is that the ship moves in response to the wave motion. Existing standards require a relatively steady liquefaction plant. As a consequence, this proposal seem possible only if great disadvantages are accepted. In addition, because of movement of the ship, there are difficulties in the transfer of the liquefied gas to a tanker.